Utilizing RS485 signal

Discussion in 'The Projects Forum' started by Transition, Jul 6, 2011.

  1. Transition

    Thread Starter New Member

    Jun 8, 2011
    8
    1
    Working on a project here to turn on a solenoid valve. Was originally told by the equipment manufacturer that it was a 5v signal used to open the valve. Turns out it's actually communicating via a serial RS485 connection. Now, i've never dealt with RS485 and quite frankly don't know where to start. What's the best way to utilize this RS485 connection?
     
  2. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,387
    1,605
    RS485 is a serial data protocol, similar to the serial port on a PC, but with different voltage levels. You can get a 484 port to add onto a PC, but having to add a computer just to turn something on may be completely absurd in your application if all you wanted as to give it 5V.

    Short version: you may have the wrong solenoid.
     
  3. Transition

    Thread Starter New Member

    Jun 8, 2011
    8
    1
    I have a laser engraver that communicates with a compressor over RS485. The laser sends this signal over RS485 to the compressor which which tells it to turn on.

    I now have multiple of these lasers and it's no longer practical to keep buying these expensive compressors. Instead, what i have done was setup a central air system and I planned on using a electronic solenoid to open/close air to the laser. The only way i know the laser needs air is when it sends out this signal via RS485.

    So what i'm asking is what is the best way(easiest, cheapest) to listen for the signal and open the valve? It is not practical to have the laser which sends the RS485 signal to be connected to a PC. The closest thing i can think of is an Arduino but they do not support RS485 out of the box.
     
  4. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    488
    Well you'll need something to analyze the signal from your laser and then give a command to your solenoid. A simple PIC (the cheapest one you can find) that has serial interface will do.

    Interfacing the PICs IO to RS485 is quite easy with 3 optocouplers and a 75176 bus transceiver.
     
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